Apparatus, device, and method for establishing connection to packet data network

ABSTRACT

Embodiments of the present invention provide an apparatus, a device, and a method. The method comprises: when it is detected that a position of user equipment changes, determining whether an area served by an anchor gateway through which the user equipment connects to a packet data network is consistent with an area served by a data forwarding gateway; sending, to the user equipment when a result of the determining is no, a packet data network connection release request that carries a reconnection indication; receiving a packet data network reconnection request sent by the user equipment; selecting an anchor gateway that serves an area consistent with the area served by the data forwarding gateway; connecting the user equipment to the packet data network by using the selected anchor gateway. Voice service experience of a user may be improved by using the method in the present invention.

This application is a continuation of International Application No.PCT/CN2013/086404, filed on Nov. 1, 2013, which is incorporated hereinby references in its entirety.

TECHNICAL FIELD

The present invention relates to the field of communicationstechnologies, and in particular, to an apparatus, a device, and a methodfor establishing a connection to a packet data network.

BACKGROUND

When a user equipment (UE) is performing a Voice over Internet Protocol(VOIP) service in a packet switched (PS) domain of a System ArchitectureEvolution (SAE)/Long Term Evolution (LTE) network, an LTE voice servicebased on an IP multimedia subsystem (IMS) network is referred to as aVoLTE service. The service has an independent access point name (APN),and the UE creates a corresponding packet data network (PDN) connection.A default bearer is QCI 5 and is used to bear Session InitiationProtocol (SIP) signaling. When the UE has a voice service, a policycontrol and charging (PCC) architecture triggers a network side tocreate a dedicated bearer QCI 1 to bear voice.

After a High Speed Packet Access (HSPA) network is deployed, IP voicebased on an IMS network is gradually applied, and this kind of voiceapplication is generally referred to as a VoHSPA service. The HSPAnetwork is formed by upgrading a previous UMTS Terrestrial Radio AccessNetwork (UTRAN). A serving general packet radio service (GPRS) supportnode (SGSN) on a core network side may be an S4 SGSN connected to aserving gateway (SGW), or may be a Gn/Gp SGSN connected to a gatewayGPRS support node (GGSN).

As shown in FIG. 1a , when UE is attached to an LTE network, servingnetwork elements of the LTE network separately are a mobility managemententity (MME), an SGW, and a PDN gateway (PGW) that are in an area 1(Area 1). After the UE moves from the area 1 to an area 2 (Area 2), thePGW is anchored and unchanged. That is, although the UE moves from theArea 1 to the Area 2, the PGW is still anchored in the Area 1.

Similarly, as shown in FIG. 1b , when UE is attached to an HSPA network,serving network elements of the HSPA network separately are an SGSN, anSGW, and a PGW that are in an Area 1. After the UE moves from the Area 1to an Area 2, the PGW is anchored and unchanged. That is, although theUE moves from the Area 1 to the Area 2, the PGW is still anchored in theArea 1.

Similarly, as shown in FIG. 1c , when UE is attached to an HSPA network,serving network elements of the HSPA network separately are an SGSN anda GGSN that are in an Area 1. After the UE moves from the Area 1 to anArea 2, the GGSN is anchored and unchanged. That is, although the UEmoves from the Area 1 to the Area 2, the GGSN is still anchored in theArea 1.

For example, for a VoLTE voice service, a SIP signaling stream and avoice stream are represented by the second dashed line in FIG. 1a , andthere is a detour on the SIP signaling stream and the voice stream,which is the same for a VoHSPA service, thereby affecting voice serviceexperience of a user.

On the other hand, when roaming between different public land mobilenetworks (PLMN), the user equipment still performs a voice service byusing an anchor gateway of an original PLMN. However, generallydifferent operators cannot interwork; therefore, the user equipmentcannot smoothly perform the voice service, which also affects the voiceservice experience of the user.

SUMMARY

Disclosed embodiments provide an apparatus, a device, and a method forestablishing a connection to a packet data network, so as to improvevoice service experience of a user.

According to a first aspect, an apparatus for establishing a connectionto a packet data network is provided, including:

a first determining unit, configured to: when it is detected that aposition of user equipment changes, determine whether an area served byan anchor gateway through which the user equipment connects to a packetdata network is consistent with an area served by a data forwardinggateway;

a sending unit, configured to: send, to the user equipment when a resultof the determining is no, a packet data network connection releaserequest that carries a reconnection indication;

a receiving unit, configured to receive a packet data networkreconnection request sent by the user equipment;

a selection unit, configured to select an anchor gateway that serves anarea consistent with the area served by the data forwarding gateway; and

a connection unit, configured to connect the user equipment to thepacket data network by using the selected anchor gateway.

In a first possible implementation manner, the first determining unit isspecifically configured to determine, according to a result of comparinga host name of the anchor gateway and that of the data forwardinggateway, whether the area served by the anchor gateway is consistentwith the area served by the data forwarding gateway.

With reference to the first aspect, in a second possible implementationmanner, the first determining unit is specifically configured todetermine, according to a local anchor gateway list, whether the anchorgateway is in the local anchor gateway list.

With reference to the first aspect, or the first possible implementationmanner of the first aspect, or the second possible implementation mannerof the first aspect, in a third possible implementation manner, theapparatus further includes:

a second determining unit, configured to determine whether the userequipment currently has a voice service; and

a detection unit, configured to: when a result of the second determiningunit is yes, detect whether a current voice bearer of the user equipmentis released completely; where

the sending unit is specifically configured to: if the detection unitdetects that the current voice bearer of the user equipment is releasedcompletely, send, to the user equipment, the packet data networkconnection release request that carries the reconnection indication.

With reference to the first aspect, or the first possible implementationmanner of the first aspect, or the second possible implementation mannerof the first aspect, or the third possible implementation manner of thefirst aspect, in a fourth possible implementation manner, the dataforwarding gateway is a serving gateway (SGW), and the correspondinganchor gateway is a packet data network gateway (PGW); or the dataforwarding gateway is a Gn/Gp SGSN, and the corresponding anchor gatewayis a GGSN.

According to a second aspect, an apparatus for establishing a connectionto a packet data network is provided, including:

a sending unit, configured to: when it is detected that user equipmentroams from a first public land mobile network (PLMN) to a second PLMN,send, to the user equipment, a packet data network connection releaserequest that carries a reconnection indication;

a receiving unit, configured to receive a packet data networkreconnection request sent by the user equipment;

a selection unit, configured to select an anchor gateway of the secondPLMN; and

a connection unit, configured to connect the user equipment to thepacket data network by using the selected anchor gateway.

In a first possible implementation manner, the anchor gateway is apacket data network gateway (PGW) or a GGSN.

According to a third aspect, a device for establishing a connection to apacket data network is provided, including an input apparatus, an outputapparatus, a memory, and a processor, where:

the processor is configured to perform the following steps:

when it is detected that a position of user equipment changes, determinewhether an area served by an anchor gateway through which the userequipment connects to a packet data network is consistent with an areaserved by a data forwarding gateway;

send, to the user equipment when a result of the determining is no, apacket data network connection release request that carries areconnection indication;

receive a packet data network reconnection request sent by the userequipment;

select an anchor gateway that serves an area consistent with the areaserved by the data forwarding gateway; and

connect the user equipment to the packet data network by using theselected anchor gateway.

In a first possible implementation manner, the step that the processordetermines whether the area served by the anchor gateway through whichthe user equipment connects to the packet data network is consistentwith the area served by the data forwarding gateway includes:

determining, according to a result of comparing a host name of theanchor gateway and that of the data forwarding gateway, whether the areaserved by the anchor gateway is consistent with the area served by thedata forwarding gateway.

With reference to the third aspect, in a second possible implementationmanner, the step that the processor determines whether the area servedby the anchor gateway through which the user equipment connects to thepacket data network is consistent with the area served by the dataforwarding gateway includes:

determining, according to a local anchor gateway list, whether theanchor gateway is in the local anchor gateway list.

With reference to the third aspect, or the first possible implementationmanner of the third aspect, or the second possible implementation mannerof the third aspect, in a third possible implementation manner,

after performing the step of determining that the area served by theanchor gateway through which the user equipment connects to the packetdata network is inconsistent with the area served by the data forwardinggateway and before performing the step of sending, to the userequipment, the packet data network connection release request thatcarries the reconnection indication, the processor further performs thefollowing steps:

determine whether the user equipment currently has a voice service; and

if a result of the determining is yes, detect whether a current voicebearer of the user equipment is released completely; and

the step that the processor sends, to the user equipment when the resultof the determining is no, the packet data network connection releaserequest that carries the reconnection indication includes:

if it is detected that the current voice bearer of the user equipment isreleased completely, sending, to the user equipment, the packet datanetwork connection release request that carries the reconnectionindication.

With reference to the third aspect, or the first possible implementationmanner of the third aspect, or the second possible implementation mannerof the third aspect, or the third possible implementation manner of thethird aspect, in a fourth possible implementation manner, the dataforwarding gateway is a serving gateway (SGW), and the correspondinganchor gateway is a packet data network gateway (PGW); or the dataforwarding gateway is a Gn/Gp SGSN, and the corresponding anchor gatewayis a GGSN.

According to a fourth aspect, a device for establishing a connection toa packet data network is provided, including an input apparatus, anoutput apparatus, a memory, and a processor, where:

the processor is configured to perform the following steps:

when it is detected that user equipment roams from a first public landmobile network PLMN to a second PLMN, send, to the user equipment, apacket data network connection release request that carries areconnection indication;

receive a packet data network reconnection request sent by the userequipment;

select an anchor gateway of the second PLMN; and

connect the user equipment to the packet data network by using theselected anchor gateway.

In a first possible implementation manner, the anchor gateway is apacket data network gateway PGW or a GGSN.

According to a fifth aspect, a method for establishing a connection to apacket data network is provided, including:

when it is detected that a position of user equipment changes,determining whether an area served by an anchor gateway through whichthe user equipment connects to a packet data network is consistent withan area served by a data forwarding gateway;

sending, to the user equipment when a result of the determining is no, apacket data network connection release request that carries areconnection indication;

receiving a packet data network reconnection request sent by the userequipment;

selecting an anchor gateway that serves an area consistent with the areaserved by the data forwarding gateway; and

connecting the user equipment to the packet data network by using theselected anchor gateway.

In a first possible implementation manner, the determining whether anarea served by an anchor gateway through which the user equipmentconnects to a packet data network is consistent with an area served by adata forwarding gateway includes:

determining, according to a result of comparing a host name of theanchor gateway and that of the data forwarding gateway, whether the areaserved by the anchor gateway is consistent with the area served by thedata forwarding gateway.

With reference to the fifth aspect, in a second possible implementationmanner, the determining whether an area served by an anchor gatewaythrough which the user equipment connects to a packet data network isconsistent with an area served by a data forwarding gateway includes:

determining, according to a local anchor gateway list, whether theanchor gateway is in the local anchor gateway list.

With reference to the fifth aspect, or the first possible implementationmanner of the fifth aspect, or the second possible implementation mannerof the fifth aspect, in a third possible implementation manner, afterthe determining that the area served by the anchor gateway through whichthe user equipment connects to the packet data network is inconsistentwith the area served by the data forwarding gateway and before thesending, to the user equipment, a packet data network connection releaserequest that carries a reconnection indication, the method furtherincludes:

determining whether the user equipment currently has a voice service;and

if a result of the determining is yes, detecting whether a current voicebearer of the user equipment is released completely; where

the sending, to the user equipment when a result of the determining isno, a packet data network connection release request that carries areconnection indication includes:

if it is detected that the current voice bearer of the user equipment isreleased completely, sending, to the user equipment, the packet datanetwork connection release request that carries the reconnectionindication.

With reference to the fifth aspect, or the first possible implementationmanner of the fifth aspect, or the second possible implementation mannerof the fifth aspect, or the third possible implementation manner of thefifth aspect, in a fourth possible implementation manner, the dataforwarding gateway is a serving gateway (SGW), and the correspondinganchor gateway is a packet data network gateway (PGW); or the dataforwarding gateway is a Gn/Gp SGSN, and the corresponding anchor gatewayis a GGSN.

According to a sixth aspect, a method for establishing a connection to apacket data network is provided, including:

when it is detected that user equipment roams from a first public landmobile network (PLMN) to a second PLMN, sending, to the user equipment,a packet data network connection release request that carries areconnection indication;

receiving a packet data network reconnection request sent by the userequipment;

selecting an anchor gateway of the second PLMN; and

connecting the user equipment to the packet data network by using theselected anchor gateway.

In a first possible implementation manner, the anchor gateway is apacket data network gateway PGW or a GGSN.

Voice service experience of a user may be improved by using technicalsolutions of the apparatus, the device, and the method for establishinga connection to a packet data network provided in the embodiments of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention or in the prior art more clearly, the following brieflyintroduces the accompanying drawings required for describing theembodiments. Apparently, the accompanying drawings in the followingdescription show merely some embodiments of the present invention, and aperson of ordinary skill in the art may still derive other drawings fromthese accompanying drawings without creative efforts.

FIG. 1a is a schematic flowchart of an example of a VoLTE service when aposition of user equipment changes;

FIG. 1b is a schematic flowchart of an example of a VoHSPA service whena position of user equipment changes;

FIG. 1c is a schematic flowchart of another example of a VoHSPA servicewhen a position of user equipment changes;

FIG. 2 is a schematic structural diagram of an embodiment of anapparatus for establishing a connection to a packet data networkaccording to the present invention;

FIG. 3 is a schematic structural diagram of another embodiment of anapparatus for establishing a connection to a packet data networkaccording to the present invention;

FIG. 4 is a schematic structural diagram of still another embodiment ofan apparatus for establishing a connection to a packet data networkaccording to the present invention;

FIG. 5 is a schematic structural diagram of an embodiment of a devicefor establishing a connection to a packet data network according to thepresent invention;

FIG. 6 is a schematic structural diagram of another embodiment of adevice for establishing a connection to a packet data network accordingto the present invention;

FIG. 7 is a flowchart of an embodiment of a method for establishing aconnection to a packet data network according to the present invention;

FIG. 8 is a flowchart of another embodiment of a method for establishinga connection to a packet data network according to the presentinvention; and

FIG. 9 is a flowchart of still another embodiment of a method forestablishing a connection to a packet data network according to thepresent invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following clearly describes embodiments with reference to theaccompanying drawings. Apparently, the described embodiments are merelysome but not all of the disclosed embodiments. All other embodimentsobtained by a person of ordinary skill in the art based on theembodiments of the present invention without creative efforts shall fallwithin the protection scope of the present invention.

FIG. 2 is a schematic structural diagram of an embodiment of anapparatus for establishing a connection to a packet data networkaccording to the present invention. As shown in FIG. 2, an apparatus1000 includes: a first determining unit 11, a sending unit 12, areceiving unit 13, a selection unit 14, and a connection unit 15.

The first determining unit 11 is configured to: when it is detected thata position of user equipment changes, determine whether an area servedby an anchor gateway through which the user equipment connects to apacket data network is consistent with an area served by a dataforwarding gateway.

When the position of the user equipment changes, for example, the userequipment moves from coverage of one area to coverage of another area,the first determining unit 11 needs to determine whether the area servedby the anchor gateway through which the user equipment connects to thepacket data network is consistent with the area served by the dataforwarding gateway. If inconsistent, when the user equipment initiates avoice service, a detour of a signaling stream and a voice stream in theprior art occurs, which affects voice service experience of a user.

Whether the area served by the anchor gateway is consistent with thearea served by the data forwarding gateway may be determined bycomparing whether a host name of the anchor gateway is consistent withthat of the data forwarding gateway, where if consistent, the areasserved by the two are consistent; or may be determined by searching ananchor gateway list stored locally. If the anchor gateway currentlyconnected to the packet data network is not in the local anchor gatewaylist, it is deemed that the area served by the anchor gateway isinconsistent with the area served by the data forwarding gateway;otherwise, it is deemed that the areas served by the two are consistent.

The sending unit 12 is configured to: send, to the user equipment when aresult of the determining is no, a packet data network connectionrelease request that carries a reconnection indication.

When the result of the determining of the first determining unit 11 isthat the area served by the anchor gateway through which the userequipment connects to the packet data network is inconsistent with thearea served by the data forwarding gateway, the sending unit 12 needs tosend the packet data network connection release request to the userequipment, where the release request carries the reconnectionindication.

The receiving unit 13 is configured to receive a packet data networkreconnection request sent by the user equipment.

The receiving unit 13 receives the packet data network reconnectionrequest resent by the user equipment.

The selection unit 14 is configured to select an anchor gateway thatserves an area consistent with the area served by the data forwardinggateway.

The connection unit 15 is configured to connect the user equipment tothe packet data network by using the anchor gateway that serves an areaconsistent with the area served by the data forwarding gateway.

When the receiving unit 13 receives the packet data network reconnectionrequest sent by the user equipment, the selection unit 14 selects theanchor gateway that serves an area consistent with the area served bythe data forwarding gateway, and then, the connection unit 15 connectsthe user equipment to the packet data network by using the selectedanchor gateway, which may avoid a detour of a signaling stream and avoice stream and improve voice service experience of a user.

According to the apparatus for establishing a connection to a packetdata network provided in this embodiment of the present invention, adetour of a signaling stream and a voice stream may be avoided, andvoice service experience of a user is improved.

FIG. 3 is a schematic structural diagram of another embodiment of anapparatus for establishing a connection to a packet data networkaccording to the present invention. As shown in FIG. 3, the apparatus2000 includes a first determining unit 21, a second determining unit 22,a detection unit 23, a sending unit 24, a receiving unit 25, a selectionunit 26, and a connection unit 27.

The first determining unit 21 is configured to: when it is detected thata position of user equipment changes, determine whether an area servedby an anchor gateway through which the user equipment connects to apacket data network is consistent with an area served by a dataforwarding gateway.

In this embodiment of the present invention, in a VoLTE service, theapparatus 2000 may be an MME, the corresponding data forwarding gatewaymay be an SGW, and the anchor gateway may be a PGW. In a VoHSPA service,the apparatus 2000 may be an S4 SGSN or a Gn/Gp SGSN; corresponding tothe S4 SGSN, the data forwarding gateway may be an SGW, and the anchorgateway may be a PGW; corresponding to the Gn/Gp SGSN, the dataforwarding gateway may be a Gn/Gp SGSN, and the anchor gateway may be aGGSN.

For example, UE is attached to an LTE network in an Area 1 andestablishes a connection to a packet data network such as an IMS Core,and an anchor gateway through which the connection passes is a PGW inthe Area 1. Now the UE moves from the Area 1 to an Area 2, an MMEselects an SGW according to a tracking area which the UE actuallyaccesses, and the MME compares a host name of the current SGW of the UEwith a host name of the current PGW. If the host names are consistent,areas served by the SGW and the PGW are the same, and the MME does notneed to perform a reselection operation on the PGW of the UE. Forexample, the host name of the SGW is:topon.s5.gw32.california.west.example.com, and the host name of the PGWis: topon.s5.gw31.california.west.example.com; therefore, the twogateways belong to a same area california.west.example.com.

The MME may determine, according to a local PGW list configured in theMME in addition to the areas in which the above host names are located,whether the SGW and the PGW belong to a same area. That is, it is deemedthat all PGWs not in a range of the PGW list configured locally are notPGWs in a current area.

The second determining unit 22 is configured to determine whether theuser equipment currently has a voice service.

The detection unit 23 is configured to: when a result of the seconddetermining unit is yes, detect whether a current voice bearer of theuser equipment is released completely.

The sending unit 24 is configured to: if the detection unit detects thatthe current voice bearer of the user equipment is released completely,send, to the user equipment, a packet data network connection releaserequest that carries a reconnection indication.

According to the above example, if the areas in which the SGW and thePGW are located are different, the MME determines whether the UEcurrently has a voice service (that is, whether the MME has a QCI 1bearer of a voice PDN connection). If the UE has a corresponding VoLTEvoice service, after a voice service bearer of the UE is releasedcompletely, the MME initiates a voice PDN connection release, where therelease request carries a reconnection indication. If the UE does nothave a corresponding VoLTE voice service, the MME directly initiates avoice PDN connection release and triggers the UE to reestablish thevoice PDN connection.

The receiving unit 25 is configured to receive a packet data networkreconnection request sent by the user equipment.

According to the above example, after receiving a voice PDN connectionrelease request sent by the MME, the UE initiates a reconnection requestof the voice PDN connection.

The selection unit 26 is configured to select an anchor gateway thatserves an area consistent with the area served by the data forwardinggateway.

The connection unit 27 is configured to connect the user equipment tothe packet data network by using the selected anchor gateway.

According to the above example, after receiving the reconnection requestof the voice PDN connection of the UE, the MME selects a PGW that is ina same area as the current SGW to serve the UE.

For a VoHSPA service controlled by the S4 SGSN, a procedure of theservice is as follows:

1. UE is attached to an LTE network in an Area 1 and creates a voicePacket Data Protocol (PDP) connection, and an anchor gateway of thevoice PDP connection is a PGW in the Area 1.

2. The UE moves from the Area 1 to an Area 2, an SGSN selects an SGWaccording to a tracking area which the UE actually accesses, and theSGSN compares a host name of the current SGW of the UE with a host nameof the current PGW. If areas are the same, the SGSN does not need toperform a reselection operation on the PGW of the UE. For example, thehost name of the SGW is: topon.s5.gw32.california.west.example.com, andthe host name of the PGW is: topon.s5.gw31.california.west.example.com;therefore, the two gateways belong to a same areacalifornia.west.example.com.

3. If areas in which the SGW and the PGW are located are different, theSGSN determines whether the UE currently has a voice service (that is,whether the SGSN has a secondary PDP corresponding to the voiceservice). If the UE has a corresponding VoHSPA voice service, after avoice service PDP of the UE is released completely, the SGSN initiates avoice PDP release, where the release request carries a reconnectionindication. After receiving a voice PDP release request sent by theSGSN, the UE initiates a voice PDP reconnection request. If the UE doesnot have a corresponding VoHSPA voice service, the SGSN directlyinitiates a voice PDP connection release and triggers the UE tore-initiate the voice PDP connection.

The SGSN may determine, according to a local PGW list configured in theSGSN in addition to the areas in which the above host names are located,whether the SGW and the PGW belong to a same area. That is, it is deemedthat all PGWs not in a range of the PGW list configured locally are notPGWs in a current area.

4. After receiving the reconnection request of the voice PDP connectionof the UE, the SGSN selects a PGW that is in a same area as the currentSGW to serve the UE.

For a VoHSPA service controlled by the Gn/Gp SGSN, a procedure of theservice is as follows:

After UE moves from coverage of an Area 1 to coverage of an Area 2, theGn/Gp SGSN determines whether a currently selected SGSN and GGSN belongto a same area. In a case in which the SGSN and the GGSN are not in thesame area, and the UE currently does not have a VoHSPA voice service,the SGSN initiates voice PDP deletion of the UE and triggers the UE toreestablish a voice PDP. In a process of reestablishing the voice PDP,the SGSN selects a GGSN that is in a same area as the SGSN to serve theUE. After the foregoing processing is completed, the UE registers with aGGSN of the Area 2 after moving to the Area 2, and the UE is served bythe GGSN of the Area 2.

A difference from the S4 SGSN scenario is as follows: The Gn/Gp SGSNcannot determine whether an SGSN and a GGSN belong to a same area byusing host names, and can determine, only by using a local GGSN listconfigured in the Gn/Gp SGSN, whether the GGSN is in the local list.

According to the apparatus for establishing a connection to a packetdata network provided in this embodiment of the present invention, anarea served by an anchor gateway is made to be consistent with an areaserved by a data forwarding gateway, so that a detour of a signalingstream and a voice stream can be avoided, which improves voice serviceexperience of a user; voice service traffic localization can be ensured,so that a voice service call delay is reduced, and a success rate ofvoice service establishment is increased.

FIG. 4 is a schematic structural diagram of still another embodiment ofan apparatus for establishing a connection to a packet data networkaccording to the present invention. As shown in FIG. 4, the apparatus3000 includes:

a sending unit 31, configured to: when it is detected that userequipment roams from a first public land mobile network PLMN to a secondPLMN, send, to the user equipment, a packet data network connectionrelease request that carries a reconnection indication;

a receiving unit 32, configured to receive a packet data networkreconnection request sent by the user equipment;

a selection unit 33, configured to select an anchor gateway of thesecond PLMN; and

a connection unit 34, configured to connect the user equipment to thepacket data network by using the selected anchor gateway.

When the user equipment moves between different operators, that is,roams from one PLMN to another PLMN, the sending unit 31 needs to send apacket data network connection release request to the user equipment,where the request carries a reconnection indication. Otherwise, aftermoving, the user equipment may be incapable of connecting to a packetdata network by using an original anchor gateway, which affects a VoLTEor VoHSPA voice service of the user equipment. After receiving thepacket data network connection release request, the user equipment sendsa packet data network reconnection request to the receiving unit 32.After the receiving unit 32 receives the packet data networkreconnection request sent by the user equipment, the selection unit 33selects an anchor gateway of the PLMN to which the user equipment roams,and the connection unit 34 connects the user equipment to the packetdata network by using the selected anchor gateway, so that the userequipment can successfully perform its VoLTE or VoHSPA voice service.

A VoLTE voice service controlled by an MME is used as an example. AfterUE roams from coverage of one PLMN to coverage of another PLMN, an MMEwith which the UE currently registers determines whether the UE thatgains access in a roaming area has an IMS PDN connection resource. Ifthere is the IMS PDN connection resource, and a current PLMN supports aVoLTE service of a roaming user, the MME instructs the UE to reestablishthe IMS PDN connection by using a message for initiating an IMS PDNconnection deletion request. In a process of reestablishing the IMS PDNconnection by the UE, the MME selects, for the roaming user, a local PGWto serve the UE. Specific operations are as follows:

1. UE is attached to a PLMN1 network and creates a voice PDN connection,and an anchor gateway of the voice PDN connection is a PGW of the PLMN1.

2. The UE roams from the PLMN1 to a PLMN2, and an MME selects, for theUE, an SGW2 of the local PLMN.

3. After the UE roams to a new PLMN, the MME determines that the UEroams from the PLMN1 to the PLMN2 network. If the UE currently has anIMS PDN connection, and the PLMN2 supports a VoLTE service of a roaminguser, the MME releases the IMS PDN connection of the UE and instructsthe UE to recreate an IMS PDN connection.

4. After receiving a voice PDN connection establishment request of theUE, the MME selects a PGW of the current PLMN.

A VoLTE voice service controlled by an SGSN is used as another example.After UE roams from coverage of one PLMN to coverage of another PLMN, anSGSN with which the UE currently registers determines whether the UEthat gains access in a roaming area has an IMS PDP resource. If thereexists the IMS PDP connection resource, and the current PLMN networksupports a VoLTE service of a roaming user, the SGSN instructs the UE toreestablish the IMS PDP connection by using a message for initiating anIMS PDP deletion request. In a process of reestablishing the IMS PDPconnection by the UE, the SGSN selects, for the roaming user, a localGGSN to serve the UE.

According to the apparatus for establishing a connection to a packetdata network provided in this embodiment of the present invention, whenroaming between different public land mobile networks, user equipmentcan successfully perform a voice service, which improves voice serviceexperience of a user.

FIG. 5 is a schematic structural diagram of an embodiment of a devicefor establishing a connection to a packet data network according to thepresent invention. As shown in FIG. 5, the device 4000 includes:

an input apparatus 41, an output apparatus 42, a memory 43, and aprocessor 44 (a quantity of processors 44 in a monitoring device may beone or more, and one processor is used as an example in FIG. 5). In someembodiments of the present invention, the input apparatus 41, the outputapparatus 42, the memory 443, and the processor 44 may be connected toeach other by using a bus or in another manner. That they are connectedto each other by using a bus is used as an example in FIG. 5.

The memory 33 stores a group of program code, and the processor 44 isconfigured to invoke the program code stored in the memory 33, so as toperform the following operations:

when it is detected that a position of user equipment changes, determinewhether an area served by an anchor gateway through which the userequipment connects to a packet data network is consistent with an areaserved by a data forwarding gateway;

send, to the user equipment when a result of the determining is no, apacket data network connection release request that carries areconnection indication;

receive a packet data network reconnection request sent by the userequipment;

select an anchor gateway of the second PLMN; and

connect the user equipment to the packet data network by using theselected anchor gateway.

In some embodiments of the present invention, the step that theprocessor 44 determines whether the area served by the anchor gatewaythrough which the user equipment connects to the packet data network isconsistent with the area served by the data forwarding gateway includes:

determining, according to a result of comparing a host name of theanchor gateway and that of the data forwarding gateway, whether the areaserved by the anchor gateway is consistent with the area served by thedata forwarding gateway.

In some embodiments of the present invention, the step that theprocessor 44 determines whether the area served by the anchor gatewaythrough which the user equipment connects to the packet data network isconsistent with the area served by the data forwarding gateway includes:

determining, according to a local anchor gateway list, whether theanchor gateway is in the local anchor gateway list.

In some embodiments of the present invention, after performing the stepof determining that the area served by the anchor gateway through whichthe user equipment connects to the packet data network is inconsistentwith the area served by the data forwarding gateway and beforeperforming the step of sending, to the user equipment, the packet datanetwork connection release request that carries the reconnectionindication, the processor 44 further performs the following steps:

determine whether the user equipment currently has a voice service; and

if a result of the determining is yes, detect whether a current voicebearer of the user equipment is released completely.

The step that the processor sends, to the user equipment when the resultof the determining is no, the packet data network connection releaserequest that carries the reconnection indication includes:

if it is detected that the current voice bearer of the user equipment isreleased completely, sending, to the user equipment, the packet datanetwork connection release request that carries the reconnectionindication.

In some embodiments of the present invention, the data forwardinggateway is a serving gateway SGW, and the corresponding anchor gatewayis a packet data network gateway PGW; or the data forwarding gateway isa Gn/Gp SGSN, and the corresponding anchor gateway is a GGSN.

According to the device for establishing a connection to a packet datanetwork provided in this embodiment of the present invention, a detourof a signaling stream and a voice stream may be avoided, and voiceservice experience of a user is improved.

FIG. 6 is a schematic structural diagram of another embodiment of adevice for establishing a connection to a packet data network accordingto the present invention. As shown in FIG. 6, the device 5000 includes:

an input apparatus 51, an output apparatus 52, a memory 53, and aprocessor 54 (a quantity of processors 54 in a monitoring device may beone or more, and one processor is used as an example in FIG. 6). In someembodiments of the present invention, the input apparatus 51, the outputapparatus 52, the memory 53, and the processor 54 may be connected toeach other by using a bus or in another manner. That they are connectedto each other by using a bus is used as an example in FIG. 6.

The memory 53 stores a group of program code, and the processor 54 isconfigured to invoke the program code stored in the memory 53, so as toperform the following operations:

when it is detected that user equipment roams from a first public landmobile network PLMN to a second PLMN, send, to the user equipment, apacket data network connection release request that carries areconnection indication;

receive a packet data network reconnection request sent by the userequipment;

select an anchor gateway of the second PLMN; and

connect the user equipment to the packet data network by using theselected anchor gateway.

In some feasible implementation manners, the anchor gateway is a packetdata network gateway PGW or a GGSN.

According to the device for establishing a connection to a packet datanetwork provided in this embodiment of the present invention, whenroaming between different public land mobile networks, user equipmentcan successfully perform a voice service, which improves voice serviceexperience of a user.

FIG. 7 is a flowchart of an embodiment of a method for establishing aconnection to a packet data network according to the present invention.As shown in FIG. 7, the method includes the following steps:

Step S101: When it is detected that a position of user equipmentchanges, determine whether an area served by an anchor gateway throughwhich the user equipment connects to a packet data network is consistentwith an area served by a data forwarding gateway, where if yes, go tostep S106; otherwise, go to step S102.

When the position of the user equipment changes, for example, the userequipment moves from coverage of one area to coverage of another area,it is determined whether the area served by the anchor gateway throughwhich the user equipment connects to the packet data network isconsistent with the area served by the data forwarding gateway. Ifinconsistent, when the user equipment initiates a voice service, adetour of a signaling stream and a voice stream in the prior art occurs,which affects voice service experience of a user. If consistent, theconnection to the packet data network remains.

Whether the area served by the anchor gateway is consistent with thearea served by the data forwarding gateway may be determined bycomparing whether a host name of the anchor gateway is consistent withthat of the data forwarding gateway, where if consistent, the areasserved by the two are consistent; or may be determined by searching ananchor gateway list stored locally. If the anchor gateway currentlyconnected to the packet data network is not in the local anchor gatewaylist, it is deemed that the area served by the anchor gateway isinconsistent with the area served by the data forwarding gateway;otherwise, it is deemed that the areas served by the two are consistent.

Step S102: Send, to the user equipment, a packet data network connectionrelease request that carries a reconnection indication.

When a result of the determining is that the area served by the anchorgateway through which the user equipment connects to the packet datanetwork is inconsistent with the area served by the data forwardinggateway, the packet data network connection release request is sent tothe user equipment, and the release request carries the reconnectionindication.

Step S103: Receive a packet data network reconnection request sent bythe user equipment.

The packet data network reconnection request resent by the userequipment is received.

Step S104: Select an anchor gateway that serves an area consistent withthe area served by the data forwarding gateway.

Step S105: Connect the user equipment to the packet data network byusing the selected anchor gateway.

Step S106: Remain the connection to the packet data network.

When the packet data network reconnection request sent by the userequipment is received, an anchor gateway that serves an area consistentwith the area served by the data forwarding gateway is selected, so asto connect the user equipment to the packet data network, which mayavoid a detour of a signaling stream and a voice stream and improvevoice service experience of a user.

According to the method for establishing a connection to a packet datanetwork provided in this embodiment of the present invention, a detourof a signaling stream and a voice stream may be avoided, and voiceservice experience of a user is improved.

FIG. 8 is a flowchart of another embodiment of a method for establishinga connection to a packet data network according to the presentinvention. As shown in FIG. 8, the method includes the following steps:

Step S201: When it is detected that a position of user equipmentchanges, determine whether an area served by an anchor gateway throughwhich the user equipment connects to a packet data network is consistentwith an area served by a data forwarding gateway, where if yes, go tostep S208; otherwise, go to step S202.

In this embodiment of the present invention, in a VoLTE service, anapparatus 2000 may be an MME, the corresponding data forwarding gatewaymay be an SGW, and the anchor gateway may be a PGW. In a VoHSPA service,the apparatus 2000 may be an S4 SGSN or a Gn/Gp SGSN; corresponding tothe S4 SGSN, the data forwarding gateway may be an SGW, and the anchorgateway may be a PGW; corresponding to the Gn/Gp SGSN, the dataforwarding gateway may be a Gn/Gp SGSN, and the anchor gateway may be aGGSN.

For example, UE is attached to an LTE network in an Area 1 andestablishes a connection to a packet data network such as an IMS Core,and an anchor gateway through which the connection passes is a PGW inthe Area 1. Now the UE moves from the Area 1 to an Area 2, an MMEselects an SGW according to a tracking area which the UE actuallyaccesses, and the MME compares a host name of the current SGW of the UEwith a host name of the current PGW. If the host names are consistent,areas served by the SGW and the PGW are the same, and the MME does notneed to perform a reselection operation on the PGW of the UE. Forexample, the host name of the SGW is:topon.s5.gw32.california.west.example.com, and the host name of the PGWis: topon.s5.gw31.california.west.example.com; therefore, the twogateways belong to a same area california.west.example.com.

The MME may determine, according to a local PGW list configured in theMME in addition to the areas in which the above host names are located,whether the SGW and the PGW belong to a same area. That is, it is deemedthat all PGWs not in a range of the PGW list configured locally are notPGWs in a current area.

Step S202: Determine whether the user equipment currently has a voiceservice, where if yes, go to step S203; otherwise, go to step S204.

Step S203: Detect that a current voice bearer of the user equipment isreleased completely.

Step S204: Send, to the user equipment, a packet data network connectionrelease request that carries a reconnection indication.

According to the above example, if the areas in which the SGW and thePGW are located are different, the MME determines whether the UEcurrently has a voice service (that is, whether the MME has a QCI 1bearer of a voice PDN connection). If the UE has a corresponding VoLTEvoice service, after a voice service bearer of the UE is releasedcompletely, the MME initiates a voice PDN connection release, where therelease request carries a reconnection indication. If the UE does nothave a corresponding VoLTE voice service, the MME directly initiates avoice PDN connection release and triggers the UE to reestablish thevoice PDN connection.

Step S205: Receive a packet data network reconnection request sent bythe user equipment.

According to the above example, after receiving a voice PDN connectionrelease request sent by the MME, the UE initiates a reconnection requestof the voice PDN connection.

Step S206: Select an anchor gateway that serves an area consistent withthe area served by the data forwarding gateway.

Step S207: Connect the user equipment to the packet data network byusing the selected anchor gateway.

Step S208: Remain the connection to the packet data network.

According to the above example, after receiving the reconnection requestof the voice PDN connection of the UE, the MME selects a PGW that is ina same area as the current SGW to serve the UE.

For a VoHSPA service controlled by the S4 SGSN, a procedure of theservice is as follows:

1. UE is attached to an LTE network in an Area 1 and creates a voicePacket Data Protocol (Packet Data Protocol, PDP) connection, and ananchor gateway of the voice PDP connection is a PGW in the Area 1.

2. The UE moves from the Area 1 to an Area 2, an SGSN selects an SGWaccording to a tracking area which the UE actually accesses, and theSGSN compares a host name of the current SGW of the UE with a host nameof the current PGW. If areas are the same, the SGSN does not need toperform a reselection operation on the PGW of the UE. For example, thehost name of the SGW is: topon.s5.gw32.california.west.example.com, andthe host name of the PGW is: topon.s5.gw31.california.west.example.com;therefore, the two gateways belong to a same areacalifornia.west.example.com.

3. If areas in which the SGW and the PGW are located are different, theSGSN determines whether the UE currently has a voice service (that is,whether the SGSN has a secondary PDP corresponding to the voiceservice). If the UE has a corresponding VoHSPA voice service, after avoice service PDP of the UE is released completely, the SGSN initiates avoice PDP release, where the release request carries a reconnectionindication. After receiving a voice PDP release request sent by theSGSN, the UE initiates a voice PDP reconnection request. If the UE doesnot have a corresponding VoHSPA voice service, the SGSN directlyinitiates a voice PDP connection release and triggers the UE tore-initiate the voice PDP connection.

The SGSN may determine, according to a local PGW list configured in theSGSN in addition to the areas in which the above host names are located,whether the SGW and the PGW belong to a same area. That is, it is deemedthat all PGWs not in a range of the PGW list configured locally are notPGWs in a current area.

4. After receiving the reconnection request of the voice PDP connectionof the UE, the SGSN selects a PGW that is in a same area as the currentSGW to serve the UE.

For a VoHSPA service controlled by the Gn/Gp SGSN, a procedure of theservice is as follows:

After UE moves from coverage of an Area 1 to coverage of an Area 2, theGn/Gp SGSN determines whether currently selected SGSN and GGSN belong toa same area. In a case in which the SGSN and the GGSN are not in thesame area, and the UE currently does not have a VoHSPA voice service,the SGSN initiates voice PDP deletion of the UE and triggers the UE toreestablish a voice PDP. In a process of reestablishing the voice PDP,the SGSN selects a GGSN that is in a same area as the SGSN to serve theUE. After the foregoing processing is completed, the UE registers with aGGSN of the Area 2 after moving to the Area 2, and the UE is served bythe GGSN of the Area 2.

A difference from the S4 SGSN scenario is as follows: The Gn/Gp SGSNcannot determine whether an SGSN and a GGSN belong to a same area byusing host names, and can determine, only by using a local GGSN listconfigured in the Gn/Gp SGSN, whether the GGSN is in the local list.

According to the method for establishing a connection to a packet datanetwork provided in this embodiment of the present invention, an areaserved by an anchor gateway is made consistent with an area served by adata forwarding gateway, so that a detour of a signaling stream and avoice stream can be avoided, which improves voice service experience ofa user; voice service traffic localization can be ensured, so that avoice service call delay is reduced, and a success rate of voice serviceestablishment is increased.

FIG. 9 is a flowchart of still another embodiment of a method forestablishing a connection to a packet data network according to thepresent invention. As shown in FIG. 9, the method includes the followingsteps:

Step S301: When it is detected that user equipment roams from a firstpublic land mobile network PLMN to a second PLMN, send, to the userequipment, a packet data network connection release request that carriesa reconnection indication.

Step S302: Receive a packet data network reconnection request sent bythe user equipment.

Step S303: Select an anchor gateway of the second PLMN.

Step S304: Connect the user equipment to the packet data network byusing the selected anchor gateway.

Different PLMNs are managed by different operators. When user equipmentmoves between different operators, that is, roams from one PLMN toanother PLMN, a packet data network connection release request needs tobe sent to the user equipment, and the request carries a reconnectionindication. Otherwise, after moving, the user equipment may be incapableof connecting to a packet data network by using an original anchorgateway, which affects a VoLTE or VoHSPA voice service of the userequipment. After receiving the packet data network connection releaserequest, the user equipment sends a packet data network reconnectionrequest. After the packet data network reconnection request sent by theuser equipment is received, the user equipment is connected to thepacket data network by using an anchor gateway of the PLMN to which theuser equipment roams, so that the user equipment can successfullyperform its VoLTE or VoHSPA voice service.

A VoLTE voice service controlled by an MME is used as an example. AfterUE roams from coverage of one PLMN to coverage of another PLMN, an MMEwith which the UE currently registers determines whether the UE thatgains access in a roaming area has an IMS PDN connection resource. Ifthere exists the IMS PDN connection resource, and a current PLMNsupports a VoLTE service of a roaming user, the MME instructs the UE toreestablish the IMS PDN connection by using a message for initiating anIMS PDN connection deletion request. In a process of reestablishing theIMS PDN connection by the UE, the MME selects, for the roaming user, alocal PGW to serve the UE. Specific operations are as follows:

1. UE is attached to a PLMN network and creates a voice PDN connection,and an anchor gateway of the voice PDN connection is a PGW of the PLMN1.

2. The UE roams from the PLMN1 to a PLMN2, and an MME selects, for theUE, an SGW2 of the local PLMN.

3. After the UE roams to a new PLMN, the MME determines that the UEroams from the PLMN1 to the PLMN2 network. If the UE currently has anIMS PDN connection, and the PLMN2 supports a VoLTE service of a roaminguser, the MME releases the IMS PDN connection of the UE and instructsthe UE to recreate an IMS PDN connection.

4. After receiving a voice PDN connection establishment request of theUE, the MME selects a PGW of the current PLMN.

A VoLTE voice service controlled by an SGSN is used as another example.After UE roams from coverage of one PLMN to coverage of another PLMN, anSGSN with which the UE currently registers determines whether the UEthat gains access in a roaming area has an IMS PDP resource. If thereexists the IMS PDP connection resource, and the current PLMN networksupports a VoLTE service of a roaming user, the SGSN instructs the UE toreestablish the IMS PDP connection by using a message for initiating anIMS PDP deletion request. In a process of reestablishing the IMS PDPconnection by the UE, the SGSN selects, for the roaming user, a localGGSN to serve the UE.

According to the method for establishing a connection to a packet datanetwork provided in this embodiment of the present invention, whenroaming between different public land mobile networks, user equipmentcan successfully perform a voice service, which improves voice serviceexperience of a user.

In the several embodiments provided in this application, it should beunderstood that the disclosed device and method may be implemented inother manners. For example, the described apparatus embodiment is merelyexemplary. For example, the module division is merely logical functiondivision and may be other division in actual implementation. Forexample, a plurality of modules or components may be combined orintegrated into another device, or some features may be ignored or notperformed. In addition, the displayed or discussed mutual couplings ordirect couplings or communication connections may be implemented byusing some communication interfaces. The indirect couplings orcommunication connections between the apparatuses or modules may beimplemented in electronic, mechanical, or other forms.

The modules described as separate parts may or may not be physicallyseparate, and parts displayed as modules may or may not be physicalunits, may be located in one position, or may be distributed on aplurality of network units. A part or all of the modules may be selectedaccording to actual needs to achieve the objectives of the solutions ofthe embodiments.

In addition, functional modules in the embodiments of the presentinvention may be integrated into one processing module, or each of themodules may exist alone physically, or two or more modules areintegrated into one module.

Based on the foregoing descriptions of the embodiments, a person skilledin the art may clearly understand that each implementation manner may beimplemented by software in addition to a necessary general hardwareplatform or by hardware. Based on such an understanding, the foregoingtechnical solutions essentially or the part contributing to the priorart may be implemented in a form of a software device. The computersoftware device is stored in a computer-readable storage medium, such asa ROM/RAM, a magnetic disk, or an optical disc, and includes severalinstructions for instructing a computer device (which may be a personalcomputer, a server, a network device, or the like) to perform themethods described in the embodiments or some parts of the embodiments.

The foregoing implementation manners are not intended to limit theprotection scope of the technical solutions. Any modification,equivalent replacement, and improvement made without departing from thespirit and principle of the foregoing implementation manners shall fallwithin the protection scope of the technical solutions.

What is claimed is:
 1. A device for establishing a connection to apacket data network (PDN), comprising: an input apparatus; an outputapparatus; a processor connected to the input apparatus and the outputapparatus; and a non-transitory computer-readable storage medium storinga program to be executed by the processor, the program includinginstructions to: determine, in response to detecting a change in aposition of a terminal that currently has a voice service, whether anarea served by an anchor gateway through which the terminal connects toa PDN is inconsistent with an area served by a data forwarding gateway;detect whether a current voice bearer of the terminal is releasedcompletely; send, to the terminal, in response to the determiningindicating that the area served by the anchor gateway is inconsistentwith the area served by the data forwarding gateway and in response tothe detecting that the current voice bearer of the terminal is releasedcompletely, a PDN connection release request that carries a reconnectionindication; receive a PDN reconnection request sent by the terminal;select an anchor gateway that serves an area consistent with the areaserved by the data forwarding gateway; and connect the terminal to thePDN by using the selected anchor gateway.
 2. The device according toclaim 1, wherein the instructions to determine whether the area servedby the anchor gateway is inconsistent with the area served by the dataforwarding gateway comprises instructions to determine, according to aresult of comparing a host name of the anchor gateway and that of thedata forwarding gateway, whether the area served by the anchor gatewayis inconsistent with the area served by the data forwarding gateway. 3.The device according to claim 1, wherein the instructions to determinewhether the area served by the anchor gateway is inconsistent with thearea served by the data forwarding gateway comprises instructions todetermine, according to a local anchor gateway list, whether the anchorgateway is in the local anchor gateway list.
 4. The device according toclaim 1, wherein the PDN connection release request comprises a voicePDN connection release request.
 5. The device according to claim 1,wherein one of the data forwarding gateway is a serving gateway (SGW)and the corresponding anchor gateway is a PDN gateway (PGW).
 6. A devicefor establishing a connection to a packet data network (PDN),comprising: an input apparatus; an output apparatus; a processorconnected to the input apparatus and the output apparatus; and anon-transitory computer-readable storage medium storing a program to beexecuted by the processor, the program including instructions to: send,to a terminal that currently has a voice service, in response todetecting that the terminal roams from a first public land mobilenetwork (PLMN) to a second PLMN, and detecting that a current voicebearer of the terminal is released completely, a voice PDN connectionrelease request that carries a reconnection indication; receive a voicePDN reconnection request sent by the terminal user equipment; select ananchor gateway of the second PLMN; and connect the terminal to the PDNby using the selected anchor gateway.
 7. The device according to claim6, wherein the anchor gateway is one of a PDN gateway (PGW) or a gatewaygeneral packet radio service (GPRS) support node (GGSN).
 8. A method forestablishing a connection to a packet data network (PDN), comprising:determining, in response to detecting a change in a position of aterminal that currently has a voice service, whether an area served byan anchor gateway through which the terminal connects to a PDN isinconsistent with an area served by a data forwarding gateway; detectingwhether a current voice bearer of the terminal is released completely;and sending, to the terminal, in response to determining that the areaserved by the anchor gateway is not consistent with the area served bythe data forwarding gateway, and in response to detecting that thecurrent voice bearer of the terminal is released completely, a PDNconnection release request that carries a reconnection indication;receiving a PDN reconnection request sent by the terminal; selecting ananchor gateway that serves an area consistent with the area served bythe data forwarding gateway; and connecting the terminal to the PDN byusing the selected anchor gateway.
 9. The method according to claim 8,wherein the determining whether an area served by an anchor gateway isinconsistent with an area served by a data forwarding gateway comprisesdetermining, according to a result of comparing a host name of theanchor gateway and a host name of the data forwarding gateway, whetherthe area served by the anchor gateway is inconsistent with the areaserved by the data forwarding gateway.
 10. The method according to claim8, wherein the determining whether an area served by an anchor gatewayis inconsistent with an area served by a data forwarding gatewaycomprises determining, according to a local anchor gateway list, whetherthe anchor gateway is in the local anchor gateway list.
 11. The methodaccording to claim 8, wherein the PDN connection release requestcomprises a voice PDN connection release request.
 12. The methodaccording to claim 8, wherein one of the data forwarding gateway aserving gateway (SGW) and the corresponding anchor gateway is a PDNgateway (PGW).
 13. A method for establishing a connection to a packetdata network (PDN), comprising: sending, to a terminal that currentlyhas a voice service, in response to detecting that the terminal roamsfrom a first public land mobile network (PLMN) to a second PLMN, and inresponse to detecting that a current voice bearer of the terminal isreleased completely, a voice PDN connection release request that carriesa reconnection indication; receiving a voice PDN reconnection requestsent by the terminal; selecting an anchor gateway of the second PLMN;and connecting the terminal to the PDN by using the selected anchorgateway.
 14. The method according to claim 13, wherein the anchorgateway is one of a PDN gateway (PGW) or a gateway general packet radioservice (GPRS) support node (GGSN).
 15. The device according to claim 1,wherein one of the data forwarding gateway is a Gn/Gp general PDN packetradio service (GPRS) support node (SGSN) and the corresponding anchorgateway is a gateway GPRS support node (GGSN).
 16. The method accordingto claim 8, wherein one of the data forwarding gateway is a Gn/Gpgeneral PDN packet radio service (GPRS) support node (SGSN) and thecorresponding anchor gateway is a gateway GPRS support node (GGSN).